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TPS54J061: work under high temperature

Will Wang47
Expert 7670 points
Part Number: TPS54J061

Hi team,

Customer would like to check if TPS54J061 could constant work under 85℃ for 3 years, could you help comment?

Thanks and Best Regards,

Will

  • 0
    TI__Mastermind 32350 points

    Hello Will, 

    Just to make sure we understand the question, is 85C ambient of Junction? The ambient is the temp the device is exposed to, and the junction is the junction temp inside the device that includes self heating during conversion. 

    The device is designed to operate up to 125C Junction. So it operating under junction of 85C will not be an issue.

      

    Thanks 

    Tahar

  • 0
    TI__Mastermind 18370 points

    Hello Will,

    There is no derating in the lifetime of the device if you operate at Tj (Junction temperature) of up to 125 C.

    Here is publicly available quality info TPS54J061:

    MTBF and FIT Rate Estimator

    If you take the FIT rate (0.2) and Usage Temp (55C) and plug into publicly available reliability calculator below:

     https://www.ti.com/support-quality/reliability/temperature-change-FIT.html

     

    This calculator allows a user to estimate the expected mean time between failures for a given device at a given operating point based on the FIT rate.

    For example, if we assume that your junction temperature is 40 degrees C above your ambient temperature of 85 C, meaning Tj = 125 C.

    The new FIT rate at 125 degrees C is 15.5, when definition of  FIT is:  FIT: Failures-in-Time. The number of failures per 1E9 device-hours

    If we assume a lifetime of 100,000 hours for a device, the FIT rate of 15.5 translates to 15.5 devices out of 10,000 devices will fail after 100,000 hours of operation ( 10,000 devices* 100,000 hours/device = 1E9 device-hours).

    In other words, if we operate 10,000 device, 15.5 out of those (0.155%) will fail after over 11 years of operation.

    We target for FIT rate of about 50 at max temperature, therefore FIT of 15.5 is perfectly fine.

     

    Hope this makes sense.

    Please let me know if any clarifications required.

     

    Regards,

    Yitzhak Bolurian

  • 0 in reply to Yitzhak Bolurian
    TI__Expert 7670 points

    Hi Yitzhak,

    Thanks for your feedback.

    Based on the tools you showed, the high temperature condition would get the parts a higher FIT, so this means the fail possibility is higher at high temperature compared to low temperature, right?

    And for your calculation below, does it also mean (3year/11year) * 15.5 = 4.227pcs would get fail over 3 years? Does my understanding correct?

    Yitzhak Bolurian said:
    In other words, if we operate 10,000 device, 15.5 out of those (0.155%) will fail after over 11 years of operation.

    Thanks and Best Regards,

    Will

  • 0 in reply to Will Wang47
    TI__Mastermind 18370 points

    Hi Will,

    Yes.  The failure chance is higher at high temperature compared to lower temperatures.

    And yes, that means that at junction temperature of 125 C, 4.227 devices out of 10000 devices may fail in 3 years.

    But please note that the junction temperature of 125 C was just an example.

    The real junction temperature in your application may be lower or higher than 125 C.
    This depends on how good your layout in terms of thermal dissipation is.

    You could measure the temperature of your device at full load using a thermal camera.
    The junction temperature should be slightly (+5 C) higher than the top case temperature of your device.

    For example, if the measured case temperature is 30 C higher than the ambient temperature.
    Then you add the ambient temperature and extra 5 C to get into the junction temperature at 85 C, meaning Tj= 30+85+5 = 120 C.

    The you run the FIT tool for 120 C.

    Hope this makes sense.

    Regards,

    Yitzhak